ALright, I have beat the temple...but nothing bothers me more than doors left unopen and things left undone. The hole that your inner voice says is very deep, but you cannot fit through. It has serpent statues on 2 cornors etc. etc... What do you do there? It obviously isnt needed to beat the area, because I have done just that. But who knows what useful items I left behind, or what I am missing out on by not finding out what it does. Anyone know?

I think it's only to give the room the "flair" of what it is: an arena. when you switched the lever and the gate closes, some apes run to you and fight. You made it, but did it also the previous candidates? And where to put their remains? Imagine yourself

I think it is a feeding chute for the Naga. Pull the lever, out come the monkeys, which fall in the hole, which land in the room below, containing the Naga. No connection to solving anything in the Snake Temple, though.